Rosin-modified phenol-formaldehyde resin coating compositions



Patented June 12, 1945 ROSIN MODIFIED PHENQL FORMALDE- E RESBI QCDA'EWGCED/ POSITIONS Robert C. Swain, Riverside, and Pierrepont Adams,Stamford, Conn, assignors to American Cyanamid Company, New York, N. Y.,a corporation of Maine No Drawing. Application December 5, 1940, SerialNo. 368,634

4 Claims.

This invention relates to coating compositions containing rosin-modifiedphenol-formaldehyde resin and melamine-formaldehyde resins.

An object of this invention is to improve the physical and chemicalproperties of coating compositions containing rosin-modifiedphenolformaldehyde resin, e.. g., acid resistance, solvent resistance,heat resistance, etc.

Another object of this invention is to provide compositions containingrosin-modified phenolformaldehyde resin and compatible proportions ofcompatible melamine-formaldehyde resins.

These and other objects are attained by blending rosin-modifiedphenol-formaldehyde resin with' a melamine-formaldehyde resin which hasbeen alkylated with an alcohol containing at least 4 carbon atomswherein the molal ratio of formaldehyde to melamine is at least about4:1.

The following examplesin which the proportions are in parts by weightare given by way of illustration and not in limitation.

Example 1 Parts Melamine-formaldehyde resin A 10 Rosin-modifiedphenol-formaldehyde resin 90 Example 2 Rosin-modifiedphenol-formaldehyderesin- '75 A composition containing these ingredientsis prepared by admixing 50 parts of melamineformaldehyde resin Bsolution (50% resin) with 150 parts of rosin-modifiedphenol-formaldehyde resin stock solution. Films of the composition areapplied to metal objects and baked at a temperature of about 135 C. forabout onehalf hour. The product formed is a very hard, clear coating.

Example 3 Parts Melamine-formaldehyde resin 'B"- Rosin-modifiedphenol-formaldehyderesin--- Parts Melamine-formaldehyde resin 13 25 Acomposition containing these ingredients is prepared by admixing 150parts of melamineformaldehyde resin B solution (50% resin) with 50 partsof rosin-modified phenol-formaldehyde resin stock solution. Films of thecomposition are aplied to metal objects and baked at a temperature ofabout 135 C. for about one-half hour. A clear, tough him is formed.

Example 4 Parts Melamine-formaldehyde resin C 50 Rosin-modifiedphenol-formaldehyde resin--- 50 A composition containing theseingredients is prepared by admixing parts of melamineformaldehyde resinC solution (50% resin) with 100 parts of rosin-modifiedphenol-formaldehyde -resin stock solution. Films of the composition areapplied to metal objects and baked at a temperature of about C. forabout one-half hour. A water-white film having good chemical propertiesis formed.

Example 5 Parts Melamine-formaldehyde resin D, 90 Rosin-modifiedphenol-formaldehyde resin--- 10 A composition containing theseingredients is prepared by admixing parts of melamineformaldehyde resinD solution (50% resin) with 20 parts of rosin-modifiedphenol-dormaldehyde resin stock solution." Films of the composition areapplied to metal objects and baked at a temperature of about 135 C. forabout one-half hour. A hard, transparent film is produced.

The

pared by heating with agitation rosin and a phenol-formaldehydecondensate until the water of condensation is distilled off, optionallyadding a relatively small proportion of an nail-unsaturatedpolycarboxylic acid such as fumaric or maleio acid and finallyesterifying the product with an alcohol such as glycerol.

Preparation of melamine-formaldehyde resin A Parts Melamine fl mol) 126Formalin (4 mols) (37% formaldehyde in water) 324.4

n-Butanol 440 This mixture is placed in a reflux apparatus which isprovided with a condenser and a suitable water trap through which thereflux conrosin modified phenol-formaldehyde resins used in the aboveexamples may be prechamber and in which the essentially aqueous fractionof the condensate may be separated from the essentially non-aqueousfraction and means is provided so that the former fraction may be drawnoii if desirable. The reaction mixture is refluxed at a temperature ofabout 91-93 C. at atmospheric pressure for 6-12 hours. The water isremoved by azeotropic distillation from the reaction mixture during thereflux operation beginning perferably about. after 2-5 hours haveelapsed and the water so removed is' separated from the refluxcondensate in the water trap. During the distillation about 550additional parts of butanol are added gradually. When the refluxcondensate is substantially anhydrous the vapor temperature will beabout 100-l05 C. The pressure is lowered sufliciently to reduce thevapor temperature to about 85-90 C. and the resin solution isconcentrated to about 60-70% solids by vacuum distillation. Theresulting resin solution may be diluted to about 50% solids with anydesired solvent or diluent, e. g., xylene.

Preparation of melamine-formaldehyde resin B Parts Melamine 283 Formalin(37% formaldehyde in water) 978 This mixture is heated at about 7080 C.until a homogeneous solution is obtained. The pH is adjusted to about7.3 with caustic soda and vacuum concentrated to' remove about 50-60% ofthe free water. Suflicient phosphoric acid is added to neutralize thecaustic soda p esent and then 320 parts of methanol are added. Wetmethanol is gradually distilled off from the mixture and dry methanol isadded at about the same rate as wet methanol is distilled ofi. Thisdistillation and addition of methanol is continued until the distillateis substantially dry methanol. During this operation which requiresabout 4 hours, about 1600 parts of methanol are added.

707 parts of "Pentasol (trade name of Sharples Solvents Corporation formixed amyl alcohols) are added and the distillation is continued untilthe vapor temperature rises to about 100-105 C. About 710 parts of thedistillate are collected. The pressure is lowered sufiiciently to reducethe temperature to 8090 C. and 178 parts more of the distillate arecollected, leaving as a product a resin solution containing 50% of resinsolids in Pentasol."

Preparation of melamine-formaldehyde resin "6 Parts Melamine-(1 mol) 126Formalin mols) (37% formaldeyde in water) 405.5 n-Hexyl alcohol 500Methyl alcohol 200 densate passes on its return to the reaction refluxoperation beginning preferably after about 2-5 hours have elapsed andthe Water so removed is separated from the reflux condensate in thewater trap. When the reflux condensate is substantially anhydrous thevapor temperature will be about 100-105 C. The pressure is loweredsuificiently to reduce the vapor temperature to about -90 C. and theresin solution is concentrated to about 60-70% solids by vacuumdistillation.

This solution is essentially a hexylated resin in hexyl alcohol, all ornearly all of the methanol having been eliminated from it during thedistillation. The resulting resin solution may be diluted to about 50%solids with any desired solvent or diluent, e. g., xylene.

Preparation of melamine-formaldehyde resin D Parts Melamine (1 mol) 126Formalin (5 mols) (37% formaldehyde in water) 405.5 Benzyl alcohol 600This mixture is placed in a reflux apparatus which is provided with acondenser and a suitable water trap through which the reflux condensatepasses on its return to the reaction chamber and in which theessentially aqueous fraction of the condensate may be'separated from theessentially non-aqueous fraction and means is provided so that theformer fraction may be drawn on if desirable. The reaction mixture isrefluxed at a temperature of about 93-95 C. at atmospheric pressure for6-12 hours. The water is removed by azeotropic distillation from thereaction mixture during the reflux operation beginning preferably afterabout 2-5 hours have elapsed and the water so removed is separated fromthe reflux condensate in the water trap. When the reflux condensate issubstantially anhydrous the vapor temperature will be about l05 C. Thepressure is lowered sufficiently to reduce the vapor temperature toabout 8590 C. and the resin solution is concentrated to about 60-70%solids by vacuum distillation. The resulting resin solution may bediluted to about 50% solids with any desired solvent or diluent, e. g.,xylene.

Alkylated melamine-formaldehyde resin may be produced in accordance withthe procedures outlined above, as Well as in any other suitable manner.Aqueous syrups of melamine-formaldehyde resins may be first produced andthen alkylated either simultaneously with dehydration or subsequent todehydration. Generally the simul taneous condensation of melamine,formaldehyde and a suitable alcohol is used because of convenience. Inorder to facilitate the alkylation with the higher alcohols, e. g., theamyl alcohols, hexyl alcohols and the octanols, a low boiling alcoholsuch as methanol or butanol may be mixed with the higher alcohol,thereby assisting in removing the water and causing the reaction to takeplace readily at somewhat lower temperatures than would otherwise berequired. The low boiling alcohol is removed by distillation after thereaction is completed. Another method for producing resins alkylatedwith a higher alcohol is to alkylate the melamine-formaldehyde resinwith a low boiling alcohol such as methanol and subsequently replacingit with the desired higher'alcohol, distilling out the low boilingalcohol. The condensation may be carried out either with or without anacid catalyst and in some instances basic catalysts may desirably beutilized.

The melamine formaldehyde resins vary slightly according to minorvariations in control during their production and in some instancessmall proportions of a suitable solvent material, e. g., benzene,toluene, xylene, mineral spirits, etc., may be added to the originalsolutions of rosin-modified phenol-formaldehyde resin andmelamine-formaldehyde resin in order to produce perfectly clearsolutions if such solutions are not originally obtained.

.formaldehyde to melamine is at least about 4:1.

Butylated melamine resins wherein the molal ratio of formaldehyde tomelamine is 3:1 are compatible in proportions up to about 40% withrosinmodified phenol-formaldehyde resin while melamine-formaldehyderesins which have been alkylated with butyl alcohol wherein the molalratio of formaldehyde to melamine is 2.521 are only compatible inproportions up to about 20%. Surprisingly enough, melamine resin whichare alkylated with ethyl alcohol wherein the molal ratio of formaldehydeto melamine is about 5:1

are compatible in proportions less than 20% and greater than 80%.maldehyde to melamine than 6:1 may be used, it is generally undesirableinasmuch as formaldehyde is lost during the curing so that usually theproduct in its cured condition doe not contain more than about 6 mols offormaldehyde to 1 mol of melamine. The percentage composition in eachinstance in this paragraph is on a total solids Weight basis.

The resins may be alkylated with an of. the straight chain or branchedchain alcohols containing at least 4 carbon atoms, preferably 4-8 carbonatoms, as well as with alkyl types of alcohols such as benzyl alcohol.The term alkylated melamine-formaldehyde resin is intended to denotecompositions which are reacted with an al- I While higher ratios offorindicated in the above examples. Such substances are, for instance,phosphoric acid, ammonium salts of phosphoric acid, etc.

Other resinous. compositions may be included in various coatingcompositions, e. g., urea-formaldehyde resins, alkyd resins, ethylcellulose, cellulose acetate, nitrocellulose, etc., as well as invarnishes, especially drying oil varnishes, such as those from tung oil,linseed oil, etc.

Our mixed products show improved acid resistance, solvent resistance,heat resistance, etc., as compared to rosin-modified phenol-formaldehyderesin compositions not containing melamine-formaldehyde resins.

Our compositions are useful in the manufacture of paints, industrialenamels, pigmented primers, wall sealers, etc., and particularly infurniture finishes which require a quick-drying coating. Our mixedresins are especially suitable for use in floor finishes, where theyoffer excellent resistance to abrasion and constant scrubbing. Ourproducts are valuable for use as railway and marine finishes because oftheir high. water resistance and general outdoor durability. Oneadvantage of our mixed products is their quick drying time and highgloss, rendering them particularly useful in printing inks.

Theterm compatible as used herein is intended to denote compositions,films of which are clear and homogeneous after baking.

Obviously many modifications and variations in the processes andcompositions described above may be made without departing from thespirit and scope of the invention as defined in the appended claims.

We claim:

1. A coating composition containing substantial amounts ofrosin-modified phenol-formalde hyde resin and a melamine-formaldehyderesin which has been reacted by heating until con- 1 densed withn-butanol wherein the molal ratio of formaldehyde to melamine is atleast about 4:1.

3. A coating composition containing substantial amounts ofrosin-modified phenol-formaldehyde resin and a melamine-formaldehyderesin which has been reacted by heating until condensed withn-hexylalcohol wherein the molal ratio of formaldehyde to melamine is at leastabout 4:1.

1. A coating composition containing substantial amounts ofrosin-modified phenol-formaldehyde resin and a melamine-formaldehyderesin which has been reacted by heating until condensed with benzylalcohol wherein the molal ratio of formaldehyde to melamine is at leastabout 4:1.

' ROBERT C. SWAIN.

PIERREPONT ADAMS.

CERTIFICATE OF CORRECTION. Patent No. 2,578,566. June 12, 1915.

ROBERT 0-. SWAIN, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5,first column, line M7, for "alkyl" read -aralky1-; and that the saidLetters Patent should be read with this correction therein that the samemay conform to the record of the case in the Patent Office Signed andsealed this 2nd day of October, A. Di 19h).

Leslie Frazer (Seal) First Assistant Commissioner of Patents.

